MARS rover Opportunity has found evidence that the Red Planet was once wet enough for life to exist there, Nasa said last night.

MARS rover Opportunity has found evidence that the Red Planet was once wet enough for life to exist there, Nasa said last night.

But the robot has not found any direct traces of living organisms, scientists announced.

A study of a fine, layered rock by the rover detected evidence of sulphates and other minerals that form in the presence of water.

The finding suggests that if there had been life present when the rocks were formed, then the living conditions could have permitted an organism to flourish. The study, however, has found no direct evidence of life.

"Nasa launched the Mars Exploration Rover mission specifically to check whether at least one part of Mars had a persistently wet environment that could possibly have been hospitable to life," said James Garvin, a lead Nasa scientist.

"Today we have strong evidence for an exciting answer: Yes."

Opportunity and its twin rover, Spirit, are controlled by a team of scientists working at the Jet Propulsion Laboratory in Pasadena, California.